Conventional methods for the design of new drugs can be extremely difficult and time-consuming. For a new drug to be effective, it must be precisely matched to its molecular target. Moreover, once such a molecule is discovered, the new drug candidate must be soluble, bioavailable, nontoxic, and resistant to metabolic enzymes. Modifications to such a new molecule, necessary to satisfy these requirements, often have an adverse effect on the drug's therapeutic efficacy. Because of these complexities, conventional drug design can be a very costly, time-consuming process.
Recent advances in combinatorial chemistry technology have attempted to address these difficulties, however the problem of making such molecules soluble, bioavailable, resistant to metabolic enzymes, and capable of penetrating through membranes often remains unsolved.
The drug delivery industry has addressed some of these problems by incorporating drugs into carriers. In drug delivery assisted products, the time of development is somewhat shortened to approximately seven years, and the average cost is decreased. Unfortunately, many drug delivery systems still have several serious limitations in view of the problems discussed above.